Propylene is the one of the basic raw materials for the production of three major synthetic materials. In industry production, there is about 1.0%˜7% propyne existing in the C3 fraction of the oil cracking. Due to the harmful impact of propyne to the propylene polymerization reaction, the concentration of propylene in the propylene gas was required to be below 5 ppm. Nowadays, the newly developed propylene-polymerization catalysts require a much lower concentration of propyne, which is below 1 ppm. The separation and purification of propylene is one of the most important tasks in the petrochemical industry. Otherwise, propyne is an important chemical that has wide applications, it is imperative to efficiently separate propyne.
To removal propyne from propylene, the conventional industrial method is the catalytic selective hydrogenation. The selective hydrogenation technologies mainly includes: C3 gas phase selective hydrogenation, C3 liquid phase selective hydrogenation and catalytic-distillation.
Chinese Patent 85106117.6 disclosed a kind of technology, in which one-stage adiabatic trickle bed reactor was used, and the catalyst used was highly selective. Patent CN102249836A disclosed a method for the preparation of highly selective hydrogenation catalyst. The active component Pd of the catalyst showed specific crystal structure and reactivity, and it can run stably for long period. Patent CN102040446A disclosed the method of employing catalytic distillation, taking advantage of the low concentration of propylene, to reduce the probability of the side-reaction of converting propylene into propane. However, the above described hydrogenation technologies are easy to over-react and then convert propylene into propane. In addition, all these catalysts are noble metals, resulting high costs. Further, the catalysts were easily be poisoned, trace amount of water, carbon monoxide, sulfur chemicals, C4 fractions, arsenic will poison these catalysts. Therefore, it is imperative to control the concentration of trace chemicals, reaction temperature and pressure in the hydrogenation technology, resulting in high cost.